The Vietnam era is as wrenching now as it was 30 years ago when Vietnam Veterans Against the War staged a night’s bivouac on the Battle Green of Lexington, MA, as a symbolic act of civil disobedience in the cradle of democracy. Filmmakers Bestor Cram and Mike Majoros have used some astonishing archival footage to recreate the emotional turmoil that marked America during its war with Vietnam. Henryk Gorecki’s 3rd Symphony provides the movie with its narrative momentum, but it’s the melding of music and image that gives the movie an overwhelming power.